Lubricating foam balance deep oil well pumping unit



y 956 A. BLACKBURN 2,756,602

LUBRICATING FOAM BALANCE DEEP OIL. WELL PUMPING UNIT Filed Nov. 25, 1953 5 Sheets-Sheet 1 v /5 Lam/5e 4 5446465020,

A /A/VA/702.

July 31, 1956 L. A. BLACKBURN LUBRICATING FOAM BALANCE DEEP OIL WELL PUMPING UNIT Filed NOV. 25, 1953 5 Sheets-Sheet 2 y 1956 1.. A. BLACKBURN 2,756,602

LUBRICATING FOAM BALANCE DEEP OIL WELL PUMPING UNIT Filed NOV. 25, 1953 5 Sheets-Sheet 3 VII/22 522 whi 7 II, I,

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LUBRICATING FOAM BALANCE DEEP OIL WELL PUMPING UNIT Filed Nov. 25, 1955 5 Sheets-Sheet 4 I IIIIIII'I'IA July 31, 1956 I L. A. BLACKBURN LUBRICA'I ING FOAM BALANCE DEEP OIL WELL PUMPING UNIT Filed Nov. 25, 1953 5 Sheets-Sheet 5 7a 55' E 20 29 7 4 62 47- I 5 Haw I 5,, H1 5 9 5 6a 68 Z Z5 Lam a2 7. 5446x510? firraelv United States Patent Ollice 2,756,602 Patented July 31, 1956 LUBRICATING FOAM BALANCE DEEP OIL WELL PUMPING UNIT Luther A. Blackburn, Los Angeles, Calif. Application November 25, 1953, Serial No. 394,405

11 Claims. (Cl. 74-37) This invention relates generally to long-stroke pumping jacks adapted particularly for use in actuating oil well pumps, and contemplates more specifically a chain-operated unit characterized by the inclusion of mechanism for counterbalancing the load by pressure of a foam lubricant providing a foam-lubricant balance operable to equalize velocities of the unit on alternate strokes of the pumps.

Pumping jacks of the type with which the present application is concerned comprise generally upright frames in which vertically-disposed endless chains are driven for the corresponding reciprocation of a crosshead by which the polish rod or sucker rod string, extending into the well is actuated' In accordance with the construction of conventional-type oil well pumps, on the upstroke of the crosshead, the weight of both the rod string and fluid column in the well is raised, whereas on the down stroke the weight of the fluid column is sustained by the tubing string, and the crosshead and the power source of the pumping jack is relieved of this weight. In order to more equally distribute the load during successive strokes of the crosshead, counterweights are utilized to oppose the motion of the crosshead on the down stroke and to counterbalance part of the load on the upstroke. In pumping deep wells, the load to be carried is very great and the cost of the counterweights is accordingly an important consideration tending to limit the utility of. such equipment.

The assumption of a large part of the load by the rod string at the beginning of each upstroke and the transfer of this portion of the load'to the tubing string during the down stroke causes considerable stretching and contraction of the rod string. The number of strokes per minute is largely limited by the tendency of too rapid reversal of movement of the rod string to result in the fracture of the rods. Accordingly, a long stroke with a corresponding minimum number of strokes per unit of pump piston travel is conducive to greater efliciency and longer life of the rod string. A reduction in the velocity of the crosshead and rod string at each end of the stroke with a corresponding acceleration intermediate the ends of the stroke, if properly controlled, contributes to minimizing the shock of reversal of the direction of movement of the string. However, accurate control of the application of power to the unit to achieve effective continuing variable regulation of the speed of the unit in proportion to the changing tension upon the rod string has heretofore been, found to be impractical.

It is a general object of the present invention to provide a pumping jack comprising a crosshead movable vertically in a suitable supporting structure in response to actuation of endless chains and incorporating a foam lubricant balance mechanism operable to compensate for variation in the load imposed during successive strokes of the crosshead.

More specifically, it is an object hereof to provide foam balancing elements comprising a piston and cylinder assembly, one of said elements being connected to the crosshead and the other carried by the frame, in combination with means to supply foam lubricant under pressure to said cylinder to cushion and retard the downward movement of the crosshead and coincidentally supplement the principal power source in elevating the crosshead and rod string during the effective power stroke.

Another object is the provision of means to continuously provide lubrication in the form of a foam seal between the cylinder and piston throughout the range of their relative reciprocating movement, the compressible foam lubricant completely filling the pressure tanks and the cylinder during pumping operation.

Another object is to provide a crosshead embodying a floating yoke interposed between actuating chains and the load to partially absorb the shock of the unit incident to reversal of the directionv of reciprocal rod travel so as to decelerate the movement of the rod string at the end of each stroke, while maintaining substantially uniform the application of power to the unit.

Still another object is to provide a pumping unit of the type referred to embodying a centrifugal switch mechanism associated with the drive shaft of the unit and operable to short circuit the engineby which the unit is actuated whenever the speed of the shaft exceeds a predetermined speed, as might otherwise occur in the event of the parting 'of the rod string.

Numerous other objects and salient features of my invention such, for example, as the provision of a crosshead which is hydraulically balanced throughout the range of its movement, elimination of lateral stress upon the rod string incident to the embodiment of guides to assure direct line application of power thereto from the crosshead, and the provision of. novel mechanism for facilitating displacement of the entire unit from above the well when service to either the well or the unit is required, will be apparent to those skilled in the art from an examination of the following description read in the light of the accompanying drawings, in which:

1 is a side elevation of a pumping unit embodying my invention;

Fig. 2 is an end elevation of the assembly illustrated in Fig. 1;

Fig. 3 is a view in vertical section, partly in elevation of the foam lubricant balancing assembly;

Fig. 4 is an enlarged detailed elevation of the piston;

Fig. 5 is an enlarged sectional view through the piston assembly;

Fig. 6 is a transverse sectional view through the cylinder of the foam lubricant balance unit illustrating the relative position of the crosshead and omitting the frame;

Fig. 7 is an exploded elevation, partially broken away, of the lower end of the cylinder illustrating particularly the yoke by which the cylinder and crosshead are flexibly connected;

Fig. 8 is a plan view of one of the roller assemblies by which the unit is supported;

Fig. 9 is a fragmentary elevation of the roller assembly shown in Fig. 8;

Fig. 10 is a transverse sectional view taken on line 1010 of Fig. 9;

Fig. 11 is a perspective view of one of the roller yokes;

Fig. 12 is a vertical section through the rail and roller assembly at one corner of the supporting structure for the unit;

Fig. 13 is a perspective view partially broken away of the crosshead assembly;

Fig. 14 is an enlarged sectional view through the shockabsorbing mechanism at one end of the crosshead;

Fig. 15 is a sectional view through the switch-actuating mechanism by which the power source is deactivated;

Fig. 16 is a cross-sectional view of the valve mechanism for sealing the pressure tanks and which vents the foam lubricant from the cylinder as a safety measure in the event the sucker rod parts near the surface of the well;

Fig. 17 is a view of the hydraulic hand pump for raising and lowering the rollers by which the unit is supported;

Fig. 18 is a cross-sectional view through one of the piston and cylinder assemblies comprising the shockabsorbing mechanism shown in Fig. 15; and

Fig. 19 is an enlarged fragmentary view of the piston rings shown in Fig. 5.

Referring to the drawings more in detail, the numerals of which indicate similar parts throughout the several views, 15 designates generally each of a pair of rails disposed in horizontal, parallel relationship at opposite sides of the well for the support of the pumping unit. Each of the rails 15 comprises a pair of I-beams 16 arranged in parallel contiguous relationship. The foundation of the pumping unit comprises a pair of channel irons 17 superimposed in spaced, parallel relationship upon each of the rails. On each pair of the channels 17 of the foundation a pair of columnar foam pressure reservoir tanks 18, also serving as vertical frame components and hereafter in this description being referred to as tank members, are rigidly mounted in spaced relation so as to define the respective ends of the frame, the four vertical tank members 18 being disposed at the corners of a rectangle. The lower ends of tank members 18 are connected to one another by conduit 85. The vertical relationship of the several frame members 18 is further reinforced by oblique braces 19 and channel sections 20 secured across the sides of the frame intermediate the upper and lower ends thereof. correspondingly the upper ends of the verticals are connected together across the respective sides of the frame by transverse 2 members 21 and 22 forming a crown block.

Extending into the well is a tubing string 23 equipped at its upper end with conventional fittings for the flow of gas and oil from the well in accordance with usual practice. 24 indicates the polish rod of a sucker rod string connecting the pump piston of the pump assembly carried by the lower end of the tubing string in the well with the pumping unit comprising my invention. The polish rod 24 terminates at its upper endin the lower portion of the unit and is connected by a suitable coupling 25 (Fig. 13) to a polish rod extension 26, the latter being secured to the crosshead 29 (hereinafter more in detail described) of the pumping unit. The vertical tank membersv 18 defining the respective ends of the frame are further reinforced by a pair of transverse channels 27 (Figs. 1 and 2), the ends of which extend beyond the respective tank members 18 to which they are rigidly attached. Supported upon complementary ends of the channels 27 at each side of the unit are a pair of elongated box-frames 28 extending horizontally parallel and in spaced relation to the re spective sides of the unit frame. The channel sections are disposed to support the box frames 28 above the level of the upper end of the polish rod 24 when the crosshead 29 is at the lower end of its stroke, whereby disconnection of the polish rod from its upper extension 26 permits the unit to be moved from above the well across the rails 15 so as to expose the well for servicing when occasion requires.

Mounted upon a suitable supporting structure laterally of one end of the frame is an engine 30 by which the unit is actuated. The power of the engine is transmitted through a reduction gear 301; and by pulley 31a and. by a belt 31 to a pulley 32 carried upon a drive shaft 33 journalled in bearing blocks 34 supported on; the nearest adjacent end of the respective box frames 28.v The belt 31 and pulley 32 are preferably enclosed in a suitable housing indicated at 35. Extending transversely through. the unit in equi-spaced relation from respective ends of the frame are a pair of sprocket shafts 36, journalled in hearing blocks 37, carried by the supporting box frames 28 at opposite sides of the unit. Exteriorly of andat each side of the frame, each of the sprocket shafts 36 carries a pair of gears 38, the gears at each side of the unit being in mesh with one another so as to transmit motion from one of the shafts to the other thereof and assure correspondence in the velocity of movement of said shafts. A pair of spur gears 39 keyed to the opposite ends of the drive shaft 33 are in mesh with the nearest adjacent gears 38 at respective sides of the unit whereby the power of the engine 30 is transmitted by the belt 31, drive shaft 33, and spur gears 39, through the gears 38 to the sprocket shafts 36. The gears at each side of the unit are closed by a housing generally indicated at 40. Each of the sprocket shafts 36 has keyed thereon a pair of sprockets 41 (Fig. 2) in spaced relationship. In the upper part of the unit and in direct alignment with the sprockets 41, respectively, are four'sprockets 42 which are keyed upon shafts 43 (Figs. 1 and 2), journalled in bearings 44 supported for individual vertical adjustment by screws 45, in an obvious manner. Four endless chains 46 are operatively engaged with the four pairs, respectively, of vertically-aligned sprockets 41 and 42, proper adjustment of the screws 45 being effective to maintain the chains in taut condition. It will thus be appreciated that operation of the engine 30 is effective to move the chains 46 in unison with the links of each chain moving parallel with one another in their respective direction and at the same velocity so as to reciprocate the crosshead 29, about to be described, which is connected to links of the several chains.

A pair of guide rails 47 are vertically arranged in each end of the unit in equi-spaced distance from the opposite sides thereof and in relative opposed relation to one another. The guide rails 47 are secured across the inside surface of the transverse channel sections 20 for the frame, and together form guiding elements for reciprocable vertical movement of the crosshead 29. The crosshead (Fig. 13) is rectangular in form and comprises a pair of upper parallel bars 48, a pair of spaced uprights 49 at each side and a pair of lower horizontal bars 50, all rigidly secured together. A pair of rollers 51, journalled on a pin 52 extending between corresponding ends of the lower bars are engageable with the respective complementary guide rails 47. Similarly, an upper pair of rollers 53, journalled between the uprights 49 at each side of the crosshead frame resists lateral displacement of the crosshead throughout its range of vertical movement. Between the lower bars 50 of the crosshead, a floating crosshead member 54 is supported in a manner about to be described for relative vertical movement with respect to the crosshead frame. The member 54 is centrally bored to permit projection therethrough of the upper end of the polish rod extension 26 which is secured in the crosshead by a polish rod clamp 55 normally seated upon a bridge 56 secured to the lower bars 50 of the crosshead frame so as to permit a range of vertical movement of the floating inner member 54 relative thereto. Between the lower bars 50 of the crosshead 29 at each end of the floating inner member 54 is a cylinder 57, welded to the bars 50. A plate 58 is secured by suitable means to each end of the floating member 54 and is formed with a lateral projection 59 (Fig. 14) which extends reciprocably through a vertical slot 60 in the adjacent cylinder 57 for attachment to an elongated piston 61 within the cylinders. It will thus be observed that the floating member is vertically movable relative to the crosshead frame within limits defined by the ends of the slots 60 in the cylinders 57. The ends of each cylinder are sealed by plugs 62. The opposite ends of each cylinder are communicated through an axial bore 63 in the piston 61 with a plug valve 63a in the end of the axial bore to govern the flow of liquid so as to permit the flow of a suitable liquid supplied to the cylinder by gravity from a reservoir tank 64 through tubes 65. Each of the tubes 65 is equipped with a suitable ball check valve 66 to prevent a return flow of the fluid in response to the movement of the piston 61, as will appear.

The crosshead 29 is connected to the chains 46 by a pair of arms 67, pivoted in the floating members 54 for movement of their ends through arcs parallel to the planes of the respective sprockets 41 and 42. Journalled in the upper end of each arm 67 is a rod 68 slotted in each end with pins 68a to engage the chains, and with a self-aligning bearing 69a in the center. The ends of the rods project laterally into the planes, respectively, of the chains 46 at opposite sides of the crosshead 29. The outer ends of each rod 68 are formed with master chain link assemblies 69, of a type disclosed in my application, Serial No. 696,986, filed September 14, 1946, now Patent 2,544,485. The link assemblies 69 are engageable in the chains 46 and form a part thereof, whereby each rod 68 moves with the two chains at opposite sides of the crosshead 29 and at the corresponding end of the frame throughout their circuits. The axes of pivoting of the arms 67 to the crosshead floating member 54 are aligned with the innermost reaches of the chains 46 to which the respective arms 67 are connected, whereby, with the rod-engaging links 69 disposed in the inner reaches of the chains, each arm is vertically disposed as seen in Fig. 1. As the rod-engaging links 69 pass upwardly through the arc of the upper sprockets 42, and thence move into the outer downwardly moving reaches of the respective chains 46, the arms 67 are swung laterally and bear upon oblique bearing plates 70, welded or otherwise attached to the upper ends of the vertical plates 58, connected between the floating member 54 and pistons 61.

The floating pistons 61 operate to slow down the reversal of the crosshead 29 and to act as an aid in cushioning the reversals, and also to absorb the shock that occurs immediately after each reversal at both ends of the stroke due to the plunger pick-up of the oil column in the tubing, as the traveling valve in the plunger closes at the beginning of the upstroke. As the lower reversal of the crosshead 29 occurs, the pistons 61 having reached the bottom of cylinder 57 due to the fluid having passed through bore 63 at a fixed rate of flow through the plug valve 63a, the pistons 61 begin to move upward, with the fluid passing from the upper chambers of cylinder 57 to the lower chamber of the cylinder. This absorbs the shock that occurs in the plunger at the lower end of the sucker rod stroke, due to the closing of the traveling valve, and the pick-up of the oil column. Then as the reciprocating crosshead 29 reaches the peak of the upstroke, the pistons 61 will have reached the top or peak travel in cylinder 57. As the reciprocating crosshead makes its reversal at the top of the stroke, the standing valve of the pump assembly closes in the working barrel at the bottom of the well and the travelling valve opens in the plunger, resulting in a shock Wave transmitted from the lower reaches of the sucker rod to the floating crosshead 54. This shock is absorbed by pistons 61 by means of the fluid passing from the lower chambers to the upper chambers in cylinder 57 as the crosshead 29 moves downwardly.

It will be observed that with power applied to the unit so as to move the inner reaches of the respective chains 4-6 upwardly, a direct pull of the chains is transmitted to the crosshead through the vertically-disposed arms 67 thus raising the crosshead and polish rod 24. On the downstroke of the crosshead 29 the unit will have been relieved of the weight of the fluid column in the tubing string 23, and the weight of the rod string which tends to lower the crosshead will make unnecessary the application of power to the unit, and accordingly, no substantial stress will be applied to the arms 67 or their connectives when the arms are in diverging relationship.

In order to equalize the velocity of the polish rod 24 on opposite strokes, and specifically to avoid excessive velocity on the downstroke with the corresponding racing of the power unit, I provide a foam-lubricant balance assembly comprising a cylinder 71 which is reciprocable with the crosshead through an opening defined by the transverse members 21 and 22 forming the crown block. The lower end of the cylinder 71 is equipped with a pair of laterally-projecting, diametrically opposed ears 72 (Fig. 6) to which are attached the opposite corresponding ends of a yoke 73. The yoke 73 is attached to the ears by pins 74, (Fig. 6) the pins fitting in holes 74a (Fig. 7) the intermediate portion of the yoke extending beneath the cylinder 71 being received between and connected pivotally at hole 48a, by a pin to the upper top center bars 46 of the crosshead, allowing flexibility between -the cylinder 71 and the cross head 29 so that the cross head 29 will not be rigid in the cylinder 71- during the upper reversal of the crosshead. The upper part of the cylinder 71 is formed with a series of vertical ribs 75 which are engageable by rollers 76 carried on standards 77 mounted upon the crown block 21 22 of the unit so as to guide the cylinder 71 in vertically-reciprocable travel. A valve 180 (Fig. 3) provided for foam testing purposes by means of a tube 181 which projects through the top of the piston 78 and which has its lower end terminating in the valve 180.

78 indicates generally a hollow piston, supported within the cylinder 71 by a pair of pipes 79 and 80 having their lower ends mounted upon a base plate 81 carried by two pair of opposed channels 27 adjacent the lower part of the frame- (Fig. 3), and extending horizontally beneath the box frame 28 from which they are suspended. The pipes 79 and 80 are vertically disposed in eccentric relationship with the cylinder 71 and piston 78, as seen in Fig. 3. The pipes 79 and 80 are connected at their lower ends with four foam lubricant pressure reservoir tanks 18 by conduits 82, 83 and 85, so as to supply foam lubricant under the pressure of a pump 84 to tank members 18 and to the cylinder above the piston 78. To this end the upper ends of the pipes 79 and 80 extend into and communicate with lateral parts in the piston through which parts foam pressure is supplied to the cylinder to counterbalance the load in the well, and also provide a foam lubricant seal between the piston 78 and cylinder 71 and for lubricating these elements.

The piston is formed with an axial bore into which an oil collection tube 87 is fitted (Fig. 5). The lower end of the tube 87 depends below the piston 78 and accommodates a reciprocating plunger 88, projecting from the lower end of the tube. The plunger is normally suspended by a helical spring 89, the upper end of which encircles the lower end of the tube and is retained thereon by a pair of lateral pins 90. The lower end of the spring is secured by suitable means to a washer 91, mounted upon the corresponding end of the plunger 38. Within the piston '73 the upper bore of the tube 87 is closed by a plug 92 having a longitudinal passage 93 therethrough which communicates with a recess in the top of the plug forming a valve cage 94. A port 95 in the top of the piston 73 communicates the valve cage 94 with the bore of the cylinder 71 thereabove. A ball check valve 96 within the cage 94 normally seals the passage 93 so as to prevent downward flow of oil from within the cylinder on top of the piston 78 through the plug 92. The piston 78 is provided with a plurality of conventional rings 97 carried in annular, peripheral grooves 98. Intermediate the top and bottom of the piston 78 an annular oil collecting groove 99 is formed in the periphery of the piston. Oil accumulating in the groove 99 during reciprocable travel of the cylinder 71 in response to movement of the crosshead 29 is permitted to flow into the bore of the piston 78 through a series of ports 100 and from the bore of the piston into the bore of the tube 87 above the plunger 88 through ports 101 in the latter tube. In order to permit the free gravitation of oil into the bore of the tube 87, a vent passage 102 is formed in the plug 92 and wall of the tube 87 which communicates the bore of the piston 78, exteriorly of the tube with that of the latter. Included within the passage 102 is a valve cage 103 for a check valve 104 operable to close to pressure within the tube 57, for a purpose about to be described. It will be appreciated that any foam lubricant flowing into the tube 87 above the plunger 88 will, upon elevation of the latter, relative to the piston 72, be forced upwardly through the passage 93 and into the cylinder 71 above the piston, displacing the valve 96 from its seat. This operation of the plunger 88 is resiliently resisted by the expansive urge of the spring 89 by which the plunger is returned to the lower end of its stroke, i. e., to the position illustrated in Fig. 5. Elevation of the plunger is effected on alternate strokes of the crosshead and to this end, the plunger 88 is equipped with a downwardly projecting coaxial stem 105 having threaded to its lower end a bearing plate 106, equipped with a rubber cushion 106a vulcanized to the plate 106. The stem 105 is of a length to extend through and below the lower end of the cylinder 71 a distance sufficient to abut against the upper bars 48 of the crosshead 29 when the latter is raised to the top of its stroke so as to correspondingly elevate the plunger 88 within the tube 87 and expel foam lubricant gravitating into the tube through the passage 93 and port 95 for its return into the cylinder above the piston 78. Further in each ring groove 93 is a piston ring consisting of a thin metal ring with a fiber ring vulcanized to the inside of the thin metal ring 98a, the metal and fiber ring are first placed in the piston ring groove 98 with the fiber next to the piston. Then a standard metal ring 97 is placed in the ring groove over the metal and fiber ring which arrangement prevents the foam compression above the piston from leaking around and past the piston rings from the under side of the rings. The fiber is placed next to the piston surface while the metal part of the ring is in contact with the outer ring 97.

The unit is adapted to be moved on and off" the well over the rails whenever the well requires servicing. To this end, each corner of the foundation of the frame is equipped with rollers 107 (Fig. 12) adapted to be lowered so as to elevate the entire unit upon the rollers, but which normally, with the unit in operation, are raised out of contact with the rails 15 so as to place the channels 17 directly in contact with the rails 15. A bydraulic manually operated pump 1125b (Figs. 2 and 17) is provided with check valves 112a and an oil reservoir tank 109a to supply oil for the cylinders 113a. Tubes 113b extend from the pump to each cylinder 113a each tube having a shut-off valve 111a so that the rollers can be raised or lowered separately or simultaneously. Each of the rollers 107 is journalled upon a pin 108 having its ends carried in side plates of a yoke 109 between the adjacent opposed channels 17 (Fig. 11). Each yoke 109 is journalled upon a tube 110 through which a pin 110a extends which is pivoted between the channels. A bearing bar 111, mounted between the opposite corresponding end of the yoke side plates is engaged by a hydraulic plunger 112 reciprocable within a cylinder 113a mounted on a block 113 which is supported on top of the channels 17 in vertical alignment with the bar 111. It will be appreciated by moving of the plunger 112 downwardly in their respective cylinder 113a, the several rollers 107 may be swung downwardly onto the I-beams comprising the rails 15 so as to elevate the unit upon the rollers, whereupon the entire unit may be rolled on or oil the well. This operation may be accomplished without disturbing the well fittings or polish rod 24 by lowering the crosshead 29 to a position in which the coupling 25 between the polish rod extension 26 is below the box frames 28a, whereupon disconnection of the polish rod 24 from its extension 26 permits lateral displacement of the unit over the upper end of the polish rod proper.

In order to minimize damage to either the pumping 7 unit or the well in the event of the parting of the rod string during operation, I provide an automatic cut-out for the engine 30 and a brake mechanism. Accordingly, the end of the drive shaft 33 opposite to that upon which the pulley 32 is mounted is extended through the bearings 34 and reduced in diameter. This end of the shaft 33 is enclosed by a casing 114 (Fig. 15). A pair of lugs 115 are secured to, or integral with, diametrically opposite sides of the shaft 33 so as to revolve therewith. Each lug 115 affords a pivotal mounting for a pair of actuating bell cranks 116, one end of each of which is disposed adjacent the shaft. The opposite section 117 of each crank 116 extends normally in parallel relationship with the shaft 33 overlying opposite arcs of a cap 118 slidably encompassing the end of the shaft. The ends of the sections 117 of the bell cranks 116 are weighted as at119 whereby, upon rotation of the shaft at a speed in excess of a pro-determined velocity, centrifugal force tends to swing the sections radially outward from the shaft causing the opposite ends of the I cranks to bear against the end of the cap 118 so as to shift the latter axially of the shaft and laterally of the pumping unit. A lever 120, pivoted to the side of the unit at 121 has one end projecting through an opening 122 in the casing 114, terminating in close proximity to the end of the cap 118 whereby axial movement of the latter in response to radial movement of the weighted ends 119 of the bell cranks 116, as above-described, if effective to induce tilting movement of the lever 12%. The lower opposite end of the lever (Fig. 2) is pivotally connected to a valve arm 123, by which a foam valve 124, of conventional construction, arranged in a conduit 125 leading from the foam pressure tanks 1'8, is controlled. The conduit 125, extends to one end of a brake cylinder 12), mounted adjacent the periphery of the drive pulley 32, and is normally closed by the valve 124. The tilting of the arm 120 is effective to open the valve and admit foam under pressure into the end of the brake cylinder 126 to which the conduit 125 is connected so as to axially shift a piston 127 within the cylinder. The piston rod 128 slides in a slot in the lower end of the brake arm 129 which is in turn pivotally supported upon a suitable mounting as at 130 connected to the frame. An intermediate reach of the brake arm 129, bearing a brake shoe 131, is disposed in adjacent relationship with the periphery of the pulley 32 whereby actuation of the piston 127 in. response to foam pressure, is effective to shift the brake shoe 131 into frictional contact with the pulley.

It will be appreciated that the pressure transmitted to the brake cylinder 126 will vary with the degree to which the foam valve 124 is opened, and that this operation is, in turn, variable with the extent of radial displacement of the bell crank sections 117 in response to centrifugal force. Upon reduction in the speed of operation, as a result of the application of the brake 131 or otherwise, the lever 120 and bell cranks 116 and associated mechanism are returned to their original inoperative positions in response to the tension of a helical spring 5132 connected between the lever 12.0 and a screw 133 threaded through a lug 134 mounted to the adjacent box frame 28. However, 'the brake remains closed, until the foam is released through valve 173, with lever 129 returning to its original positionv by means of a spring 179. An adjustable stop is provided to limit the projection of the lever 120 into the casing 114, comprising a slotted bar 135, secured by screws 136 to a suitable mounting below the casing. 114. It will be understood that by slidable, longitudinal adjustment of the bar 135, the range of movement of the lever 120 may be varied to meet specific requirements.

coincidentally, with the application of the brake mechanism, a switch 137 is provided to short circuit the magneto 138 of the engine 30 so as to deactivate the latter. The switch 137, which is arranged in the magneto circuit and is of conventional construction, is connected 9 to the frame adjacent to, and in alignment with, the valve arm 123, whereby movement of the latter in response to operative impetus by the governor-actuating mechanism causes the valve arm 123 to abut against a switch-actuating plunger 139 so as to close the switch 137 and short circuit the magneto.

The operation and utility of my invention is further briefiy described as follows: With the cross head 29 intermediate the ends of its upward stroke, the pivoted arms 67 of the cross head are in vertical position in engagement with the inner reaches of the respective chains 46. The power of the engine 30 is transmitted through the belt 31 and gears to the drive sprockets 41 so as to move upwardly the inner reaches of the chains 46 and thereby raise the crosshead 29 and polish rod 24 clamped therein. This upward movement of the crosshead is trans mitted to the cylinder 71 so as to enlarge the chamber within the cylinder above the piston I8. Foam lubricant pressure supplied to the latter chamber through the pipe 79 and 80 from the tank members 18 supplements the greater part of the power of the engine 30 in raising the crosshead 29, sucker rod string and fluid column during the pumping stroke. The cylinder '71, the yoke 73, and the crosshead 29 are centered in direct alignment over the well thereby lifting the sucker rod in a direct line. As the rod engaging links 629 to which the pivoted crosshead arms 67 are connected, reach the upper sprockets 42, the movement of the crosshead and reciprocating assembly is progressivelyretarded until the rod engaging links 69 reach the uppermost arc of the idler sprockets 42 and during this final upward movement of the crosshead, the upper bars 4-8 of the latter abut against the rubber face of the bearing plate 106 connected to the stem 105 of the plunger 88 so as to raise the latter and expel any foam lubricant that may have accumulated in the tube 87 of the piston 78, into the upper chamber of the cylinder 71, thereby preventing any leakage past the piston 7 8.

During the final stages of the upward movement of the crosshead 2?, the pivoted arms 67 begin to swing outwardly following the upper arcs of the sprockets 42. During the succeeding down stroke, the arms 67 are accordingly in diverging relationship (shown in phantom line, Fig. l) and the crosshead is lowered by the weight of the rod string, and engine 30, pulling against the foam pressure in the cylinder 71. The cylinder 71 is lowered with the crosshead against the foam pressure previously introduced into the upper end of the cylinder during the preceding stroke. This foam is forced by the downward moving cylinder 71 back into the tank members 18 against the foam pressure in the tank members 18 thereby balancing the well load on the downward stroke. The gravitation or downward stroke of the crosshead and rod string is at a velocity substantially equal to that of the movement of the crosshead during its upward stroke, thus preventing a sudden reversal of movement of the crosshead when the rod engaging links 69, by which the crosshead and chains 46 are connected, reach the lower sprockets 41 and the succeeding upward stroke is initiated. The velocity of movement of the crosshead on the upstroke is thus controlled by the engine, and a corresponding velocity of the crosshead and rod string is assured on the down stroke as more fully described hereafter.

In the initial operation of the unit a foam producing liquid is added to tank 147 and to reservoirs 18 to level 148 for the transformation to foam pressure for the purpose of counterbalancing the load in the well, and to act as a lubricant for the cylinder walls. The foam producing liquid when transformed to foam is sufficient to completely fill reservoirs 18 and cylinder 71 with foam. The foam pressure is maintained during pumping operations by the action of the air compressor 84. The liquid is changed from one condition to another, forming foam under pressure and a lubricating element of a type disclosed in my copending application Serial No. 246,849 filed September 15, 1951, now Patent No. 2,664,764. Without limiting myself to any particular composition of the liquid, 21 further formula is submitted illustrative of a composition which proves effective for the purpose described:

Percent Powdered soap detergcnt l0 Distilled water 50 Ammonia 3 Refined petroleum oil 37 The powdered soap detergent is dissolved in solution with water, ammonia, and petroleum oil. Upon agitation this liquid transforms completely into a foam. The ammonia causes the oil to effectively mix with the water, and also contributes to the foam-producing function. Agitation of the liquid is induced primarily by introduction of air into the mixing tank 147 and reservoirs 18 below the surface of the liquid through a screw tube 157 which is connected by a tube 156 to a compressor 84 actuated by a motor 153. During pumping operations, resulting in the reciprocation of the cylinder 71, foam within the cylinder is expelled from the latter causing a movement of the foam in the tank members 18. To maintain the characteristic condition of the foam, the foam is forced to pass back and forth from the cylinder 71 to tank members 18 by the reciprocating movement of the cylinder.

An additional satisfactory foam lubricant formula is as follows:

Percent Foam forming liquid 71 Refined petroleum oil 25 Ammonia 3 Naphtha 1 Agitation of this mixture transforms it into a lubricating foam of the proper consistency.

The formula for the above-mentioned foam forming liquid is as follows:

Percent Coconut oil soap 60 Palm-olive oil soap 23 Tallow soap 15 Ammonium sulfate l Trisodium phosphate 1 The constituents of the foam-forming liquid are dissolved in a suflicient amount of water and saponine to form a foam-forming liquid of the desired specific qualities.

The foam pressure maintained within the tank is determined by a regulator which controls the operation of the compressor 84 and is operated to actuate the compressor whenever the foam pressure falls below an amount required to counterbalance the weight of the rod string plus one-half the weight of the fluid raised by the rods during the upstroke of the latter. A generator 154 (Fig. 2) actuated by the engine 30 provides power for the motor 153. Liquid from the tank 147 may be supplied to the tank members 18 during operation of the unit by opening the valve 151'which permits it to flow into the tank members 18.

The operation of my invention is further briefly described as follows: After filling the mixing tank 147 and the reservoirs 18 to the level 148 indicated in Fig. 1 and with the cylinder in a position directly over the well with the crosshead 54 lowered and the polish rod 26 clamped thereto, the compressor 84 is energized to force air into tank 147, filling the tank members 18 and cylinder 71 with foam. The forcible expulsion of the air through the ports of the tube 157 into the liquid transforms the latter into foam, filling the reservoirs 18 and the cylinder 71 with lubricating foam under pressure. The pressure is preferably raised as above indicated, until the weight of the sucker rods and one-half of the weight of the fluid in the tubing is counter-balanced. As the fluid in the well is carried by the tubing string during the down stroke of the rods, the pressure in the cylinder 71 opposing the weight of the rods is sufiicient to maintain the pumping unit inactive. The operation is initiated by starting the engine 30 which supplies sufficient power to raise the cylinder 71 and crosshead 29, raising the rod string in the well. The engine power is transmitted through the belt 31 and gears 39 and 38 to drive the sprockets 41 continuously, moving the inner reaches of the four chains 46 upwardly, thereby raising the crosshead 29 with the rod string. During the initial phase of the upward movement of the rod string, the rods assume the weight of the fluid in the tubing. The stretching of the rods is gradually accomplished, minimizing stress on the rod string due to expansion of the foam. The pressure within the reservoir and cylinder are progressively dissipated and accordingly the velocity of the string is retarded so as to effect a slower reversal of direction of the movement at the top of the cycle. Since the rod engaging links 69 pass over the top of the arc of the upper sprockets the reversal of the rods is accomplished gradually, also reversing the cylinder 71. By the downward movement of the cylinder and rods, the lubricating foam pressure is forced back into the tank members 18. The downwardmoving rod string is progressively retarded due to the greater pressure produced in the tanks. The downwardmoving cylinder over the piston 78 effects a slower reversal of direction of the rod string as the rod engaging links 69 pass under the arc of the sprockets at the lower end of the stroke. It will be observed that disregarding the variations in pressure during the cycle of operation, the capacity of the tank members 18 and the effective load upon the engine 30 are generally measured by the power required to raise the rod string and one-half the fiuid weight. It will be understood that the compressor 84 is energized in response to actuation of the regulator 155 only when foam pressure within the tank members 18 and transmitted to the regulator through the tube 155a (Fig. 2) falls below the minimum required to counterbalance the weight of the rod string plus one-half the weight of the fluid in the well when the string is intermediate the end of its stroke.

Further, since the engine has a governor control it operates in predetermined speed ranges under varying loads automatically, which prevents the unit from stalling during any part of its pumping cycle. A safety valve 160 is provided on tank 147 so that in the event the foam pressure exceeds an amount required to counterbalance the weight of the rod string plus one half the weight of the fluid raised by the rods during the upstroke of the latter, the foam pressure is released to the atmosphere until the predetermined minimum pressure is reached.

In the event the sucker rod should part near the surface of the well, permitting the crosshead 29 to run free, a safety valve control is provided as shown in Fig. 16 which is actuated by sudden excess speed of the governor 114. This closes the pressure reservoirs 18 and vents the foam pressure from cylinder 71 to the atmosphere, thereby preventing the cylinder 71 and crosshead 29 from rushing upward uncontrolled. The governor shown in Fig. 15 opens valve 124 by arm 120 and thereby the foam pressure from reservoir 18 moves through pipe 125 to cylinder 126. This pressure moves piston 127 and stem 123 against the brake lever 129 setting the brake and in turn pulls cable 141 (Fig. 16) thereby closing valves 1 :52 and 143 and opening valve 144, venting the foam pressure from cylinder 71 to the atmosphere. Valves 14 2 and 143 shut off the foam pressure between reservoirs 18 and cylinder 71 while lever 145 opens valve 144, the two levers being connected by a yoke 146 thereby retaining the pressure in reservoirs 18 and releasing the foam pres sure from cylinder 71 by valve 144 thus maintaining the crosshead under control.

During normal operation of the pumping unit, valves 142 and 143 remain open while valve 144 remains closed. When the polish rod 24 is to be disconnected from the crosshead 29, valves 142 and 143 are closed, shutting off tank members 13, while valve 144 is opened thereby permitting the foam pressure to escape from cylinder '71 to the atmosphere and making it possible to control the crosshead when the pumping unit is moved to and from the well as the crosshead 29 must be at the lower end of the stroke when the polish rod is clamped in the crosshead 29.

it is further understood that additional lubrication for the lower part of the piston 73 and also lubrication for the four endless chains 46 is provided as follows: Tanks 161 and 162 (Fig. 3) are filled with oil. Both tanks are provided with pressure reducing valves 165 and 16S and receive foam pressure through tube 163 which tube is connected to tank members 18, the foam pressure forcing oil from tanks 161 and 162 through tube 166 to the lower part of the piston 78 into groove 167 (Fig. 4) and from tank 162 through tube 169 to and above each lower sprocket 41. Needle valves 1'70 extend over each sprocket 41, lubricating the chains 46 by dripping oil on the sprockets. Tube 163 is provided with a shut on valve 16 so as to refill the tanks 161 and 162 with oil through the top of the tank by removing plugs 1'72 and 173 (Fig. 3). An oil level gage 174 and 175 is shown attached to each tank.

While I have described and illustrated but a single embodiment of my invention, it will be appreciated that numerous changes in size, design, shape, number, and proportion of the various parts may be made, and that substitution of mechanical equivalents for the various components of the pumping unit described herein may be effected without departing from the spirit of my invention as defined by the appended claims.

I claim:

1. In a foam counterbalanced long stroke oil well pumping jack, the combination of a vertical frame, a horizontal crosshead reoiprocable up and down in said frame, means for attaching said crosshead to the polish rod component of a sucker rod string, a counterbalance cylinder carried by said crosshead for movement in unison therewith, a piston within said counterbalance cylinder; said piston being supported by said frame, a foam pressure reservoir tank, means for maintaining foam under pressure in said tank, conduit means interconnecting said reservoir tank with that portion of the counterbalance cylinder enclosed by said cylinder and piston, means for imparting reciprocation to said crosshead including unidirectionally moving endless chains disposed adjacent to said crosshead at opposite sides of said polish rod attaching means; each of said chains including parallel ascending and descending reaches, and link means connecting said chains to said crosshead whereby said unidirectional movement of said chains will reciprocate said crosshead with simultaneous reciprocation of said cylinder on said piston; said piston being supported in the counterbalance cylinder by a pipe which extends therethrough to make fluid connect-ion to the inside of the cylinder at one end of the pipe, and with the foam reservoir tank at the other end.

2. In a long stroke oil well pumping jack, the combination of a vertical frame, a horizontal crosshead guided in said frame, means for connecting the polish rod component of 'a sucker rod string to said crosshead, means for imparting reciprocation to said crosshead comprising at least two vertically disposed pairs of sprockets disposed one pair each at the opposite ends of said crosshead, each pair having an endless chain operatively engaged therewith, link means connecting said crosshead to said chains, and in which there are shock absorbing means comprising at least one shock absorber cylinder rigidly fixed to the crosshead, said shock absorber cylinder having a longitudinal slot in the side thereof, a shock 13 absorber piston in said shock absorber cylinder having a longitudinal fluid passage therethrough to pass fluid from one end of the cylinder to the other, a floating member interconnecting the sucker rod and the crosshead, said floating member having a projecting. ear which projects through the slot in said shock absorber cylinder and into said shock absorber piston, whereby fluid flow through said fluid passage absorbs shocks which accompany a change in direction of crosshead movement.

3. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod string in a well tubing string, the combination of a frame comprising four foam reservoir compression tanks sewing as vertical members, base plates on each side of the lower inner center of the said frame, two vertical pipe columns mounted upon said base plates, a piston supported in the top center of the said frame by said two vertical pipe columns, the pipe columns making a fluid passage to the top of the piston, the lower ends of the pipe columns extending to the said four vertical foam reservoir compression tanks and making fluid connection with a counterbalance cylinder in the upper center of the frame, so disposed and arranged that the piston may reciprocate therein, a crosshead pivotally connected to the lower end of the said counterbalance cylinder, a floating member restrained within the said crosshead, means interconnecting the crosshead and floating member whereby the floating member is vertically movable relative to the crosshead within limits established by said crosshead, and is engaged by the crosshead at the extreme of said limits, four pairs of vertically aligned sprockets mounted to the frame, four endless chains, each being operatively engaged with one pair of sprockets, power means for rotating the sprockets and driving all the chains continuously in the same direction, a pair of diverging arms pivotallymounted to the crosshead, each arm being connected to a different two of the chains whereby operation of the power means reciprocates the said crosshead vertically up and down between the said pipe columns and reciprocates the. said cylinder over the said piston and the said pipe columns, means for connecting said crosshead to the polish rod component of a pump, means for producing a foam lubricant within said foam reservoir compression tanks, means for maintaining said foam under pressure sufiicient to counterbalance a weight In excess of the weight of the sucker rod string and one half the weight of the fluid in the tubing string during the initial stages of the upward movement of the said sucker rod string, the crosshead and the said cylinder.

4. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod string in a well tubing string, the combination of a frame comprising four foam pressure reservoirs serving as vertical corner supports, a crosshead pivotally connected to a cylinder, said crosshead having a pair of diverging arms connected to four endless chains by means of two transverse rods, said crosshead reciprocating between four endless chains while the said chains move continuously in the same direction by means of four pairs of vertically aligned sprockets driven by a power means, a piston supported above the center of the said frame by two pipe columns, with their upper ends mounted in the said piston and with the lower ends of the pipes mounted in the lower center section of the said frame with the said pipes ex tending to the said four foam pressure reservoirs, the said cylinder being in open communication with the said foam pressure reservoirs through the said pipes, the said cylinder being closed at the upper end with an open lower end reciprocating on said piston, and over said pipe columns, with the said crosshead connected pivotally to the lower of the said cylinder by means of a. yoke, the lower end of the cylinder having a pair of ears on each side, with the upper part of the yoke connected between the ears by means of pins while the lower center part of the yoke is connected to the center of the crosshead by means of a pin, said crosshead being connected flexibly to the cylinder yoke, with said crosshead reciprocating between the said pipe columns, said crosshead having a sucker rod string clamped thereto, the said supporting pipe columns projecting into the open end of the said cylinder, means for producing a foam lubricant Within said foam pressure reservoirs, means for maintaining said foam under pressure suflicient to counterbalance a weight in excess of the weight of the sucker rod string and one half the weight of the fluid in the tubing string during the initial stages of the upstroke of the said rod string and cylinder.

5. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod in a well tubing string, the combination of a frame, comprising four foam compression reservoir tanks serving as corner supports in the said frame, with a crown section resting upon the said supports, a piston supported in the top center of the said frame crown section by two vertical pipe columns, their lower ends connected to the said foam pressure reservoir tanks, a cylinder with its upper end closed and its lower end open reciprocating over the said piston, the said cylinder being in open communication with said foam reservoir tanks through the said pipe columns, said cylinder receiving suflicient foam pressure therefrom to counterbalance a weight in excess of the weight of the sucker rod string and one half the weight of the fluid in the tubing string during the initial stages of the upstroke of the said rod string and cylinder, a crosshead pivotally connected to the lower end of the said cylinder by means of a yoke, means for connecting said crosshead to the polish rod component of a pump, a floating member within the said crosshead having a pair of diverging arms connected to four vertical chains by means of transverse rods extending through a self-aligning bearing in each arm, said rods having a radius or axis of rotation as the upper and lower reversals occurs in each stroke, said arms being in an upright position during the upstroke and in a diverged position during the downstroke, said crosshead being operative by means of four pairs of vertically aligned sprockets with four chains driven by a power means, the said crosshead reciprocating between the four chains, with the said cylinder projecting or jutting part way out and above the top center of the said section with each upstroke of the crosshead, the said cylinder having vertical ribs engaged by rollers and mounted upon the said crown section to act as a guide in the vertical reciprocable travel of the said cylinder, a perforated tube within a mixing tank, said tank being connected by a tube to the said foam pressure reservoir tanks, a compressor connected to said perforated tube to inject air under pressure through the perforations of the said tube into said mixing tank, a quantity of foam-producing liquid in said tanks to fill the said tanks with foam with response to actuation of said compressor, and by the reciprocating of the said cylinder forcing foam pressure back and forth between the said cylin der and tanks, and means to maintain said foam under sufficient pressure to counterbalance a portion of the load upon the said crosshead during the upstroke of said rod string.

6. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod string in a well tubing string, the combination of a frame comprising four foam pressure reservoir tanks supporting the said frame being disposed at the corners of a rectangle in a vertical position, a piston in the top center of the said frame supported by two pipe columns, with their lower ends connected 'to the said four foam pressure tanks, said pipe columns being in open communication between a cylinder and the said foam pressure reservoir tanks, a crosshead pivotally connected to the said cylinder, a floating member within the said crosshead having a pair of diverging arms connected to four endless chains by means of two transverse rods, said crosshead having a sucker rod-string clamped therein, said crosshead and cylinder reciprocating between four endless chains by means of two transverse rods connecting the chains, and chains moving continuously in the same direction by means of four pairs of vertically aligned sprockets driven by a power means, said chains moving in unison With one another with the four inner strands of chain link pins moving upward and parallel with one another, and with the four outer strands moving downwardly, with the link pins parallel with one another, thereby maintaining the said crosshead in a level position, a foam mixing tank, a perforated tube within the said mixing tank, said tank being connected to the said foam pressure reservoir tanks by means of a pipe, a compressor connected to the said perforated tube to inject air under pressure through the perforations of said tube into said tank, a quantity of lubricating foam producing liquid in said tanks to fill said tanks and said cylinder with a lubricating foam in response to actuation of said compressor and reciprocation of the said cylinder, and means to produce and maintain said foam under minimum pressure sufficient to counterbalance a load upon said crosshead in excess of the weight of the rod string.

7. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod in a well tubing string, the combination of a frame comprising four foam compression tanks serving as vertical corners of a rectangle supporting the said frame, a piston supported rigidly in the top center of the said frame by two vertical pipe columns, their lower ends mounted on each side of the lower inner center of the said frame and extending to the said foam compression tanks conveying lubricating foam pressure through the said piston to a counterbalance cylinder reciprocating on the said piston, a crosshead pivotally connected to the lower end of the said cylinder, a floating member within the said crosshead with a pair of diverging arms with transverse rods engaging four endless chains operatively engaged by four pairs of vertically aligned sprockets driven by a power means reciprocating the said crosshead between the said pipe columns and reciprocating the said cylinder on the said piston and over the said pipe columns, means for connecting said crosshead to the polish rod component of a pump, means for producing a lubricating foam pressure within the said tanks, a compressor connected to said tanks through a mixing tank to inject air under pressure through perforations in said mixing tank, a quantity of foam producing liquid in said mixing tank and in said foam compression tanks to fill said tanks with foam pressure in response to actuation of said compressor and agitation effect of the said reciprocating cylinder, and means to maintain said foam under sufficient pressure to counterbalance a portion of the load on the said crosshead during the upstroke of the said rod string and means comprising a regulator to actuate said compressor whenever pressure within said tanks falls below a predetermined level.

8. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod in a well tubing string, the combination of a frame comprising four foam compression tanks disposed vertically at the corners of a rectangle supporting the said frame, a piston supported rigidly in the top center of the said frame by two verti-- cal pipe columns with their lower ends mounted on each side of the lower inner center of the said frame and extending to the said foam compression tanks, said pipe columns conveying lubricating foam pressure through the said piston to a counterbalance cylinder, a crosshead pivotally connected to the lower end of the said cylinder, a floating member within the said crosshead with a pair of diverging arms with transverse rods having slots and pins in their ends engaging four endless chains operatively engaged by four pairs of vertically aligned sprockets driven by a power means reciprocating the said crossh between the said pipe columns while reciprocating the said balance cylinder over the piston and said pipe columns, means for connecting said crosshead to the polish rod component of a pump, the said floating member within the said crosshead having a floating shockabsorbing piston within a cylinder on each end of the said member, the said cylinders being connected rigidly to each end of the said crosshead with the said floating member ends projecting through elongated slots in the said cylinders and into a confined slot in each of the said pistons, said pistons having a bore alternately forcing fluid from one chamber to the other as the said crosshead and balance cylinder reciprocates on each stroke, said cylinder having rollers engaged thereto as the said cylinder reciprocates through the top center of the said frame, said rollers spaced so as to hold the cylinder in alignment with the said crosshead and with the said polish rod and means to maintain foam pressure in said tanks to resist and assist successive stroke repectively of said cylinder.

9. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod in a well tubing string, the combination of a frame comprising four foam compression tanks disposed vertically at the corners of a rectangle supporting the said frame, a piston supported rigidly in the top center of the said frame by two vertical pipe columns with their lower ends mounted on each side of the lower inner center of the said frame and extending to the said foam compression tanks said pipe columns conveying lubricating foam pressure through the said piston to a counterbalance cylinder, the said foam pressure lubricating the cylinder walls and acting as an effective counterbalance pressure to balance a predetermined well load, said pipe columns delivering foam pressure simultaneously to the said foam balance cylinder counterbalancing its effective movements, a crosshead pivotally connected to the lower end of the said cylinder, said crosshead having a pair of diverging arms with a pair of transverse rods having slots and pins in their ends engaging four endless chains operatively engaged by four pairs of vertically aligned sprockets driven by a power means reciprocating the said crosshead, and a polish rod extending to a well between the chains, and said pipe columns having two chains and one pipe column on each side of the said crosshead, while reciprocating the said balance cylinder over the saidpiston and said pipe column and between the said four chains, means for producing a foam lubricant within said tanks, means for maintaining said lubricant under pressure sufficient to counterbalance a weight in excess of the weight of the sucker rod string, and one half the weight of the fluid in the tubing string during the initial stages of the upstroke of the said rod string and said cylinder.

10. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod in a Well tubing string, the combination of a frame comprising four foam reservoir compression tanks disposed vertically at the corners of a rectangle supporting the said frame, a piston supported rigidly in the top center of the said frame by two pipe columns with their lower ends mounted on each side of the'lower inner center of the said frame and extending to the said foam compression tanks, said pipe columns conveying foam pressure to a counterbalance cylinder sufficient to counterbalance a given load in a well, a crosshead pivotally connected to the lower end of the said cylinder said crosshead having a pair of diverging arms with a pair of transverse rods engaging four endless chains operatively engaged by four pairs of vertically aligned sprockets driven by a power means reciprocating th said crosshead and the said cylinder, means for connecting said crosshead to the polish rod component of a well, a shut-off valve at a point in each of the said pipe columns extending to the said foam reservoir compression tanks, and a vent valve in one of the said pipes whereby the said foam tanks may be closed from the balance cylinder and the foam compression lowered 17 in the said balance cylinder by opening the said vent valve, means to produce foam pressure within said tanks and cylinder, said pressure being variable in direct relation to the movement of the said cylinder.

11. In a foam counterbalanced long stroke oil well pumping jack for actuating a sucker rod in a well, the combination of a frame comprising four foam reservoir compression tanks disposed vertically at the corners of a rectangle supporting the said frame, a piston supported rigidly in the top center of the said frame, by two vertical pipe columns with their lower ends mounted on each side of the lower inner center of the said frame and extending to said foam reservoir compression tanks which are connected together by pipes, said pipe columns conveying foam lubricant pressure from the said foam reservoir compression tanks through the said piston to a counterbalance cylinder, a crosshead pivotally connected to the lower end of the said cylinder, a floating member within the said crosshead with a pair of diverging arms With transverse rods having slots and .pins in their ends engaging four endless chains operatively engaged by four pairs of vertically aligned sprockets driven by a power means reciprocating the said crosshead between the said chains and the said pipe columns, while reciprocating the said counterbalance cylinder over the said piston and said pipe columns and between the said chains, means for connecting said crosshead to the polish rod component of a pump, means for producing a foam lubricant pressure within the said tanks, a compressor connected to said foam reservoir compression tanks through an intake and mixing tank, said compressor having connections with the said tanks by a tube with a check valve at a point in the tube, said compressor to inject air under pressure through perforations in said mixing tank, a quantity of foam producing liquid in said mixing tank and in said compression tanks to fill said tanks with foam pressure in response to actuation of the said compressor and agitation effects of the said reciprocating cylinder and means to maintain said foam under sufi'icient pressure to counterbalance a Weight in excess of the weight of the sucker rod string and one half the Weight of the fluid in the tubing string during the initial stages of the upstroke of the said rod and cylinder, and means comprising a regulator to actuate said compressor whenever pressure within said tanks falls below a predetermined level.

References Cited in the file of this patent UNITED STATES PATENTS Wilshusen Aug. 29, 1950 Blackburn Jan. 5, 1954 

